Compressor



L. J. CLAPP May 4 COMPRESSOR Filed Feb. 15, 1924 Fig.

Patented May 4, 1926.

UNITED STATES PATENT OFFICE.

LEWIS J. CLAPP, OF CLAREMONT, NEW HAMPSHIRE, ASSIGNOB TO SULLIVAN MA CHINERY COMPANY, ACORPORATION OF MASSACHUSETTS.

COMPRESSOR.

Application filed February 15, 1924. Serial No. 693,106.

To all whom it may concern:

Be it known that I, LEWIS J. CLArP, a citizen ofthe United States, residing at Claremont, in the county of Sullivan and State of New Hampshire, have invented certain new and useful Improvements in Compressors, of which the following is a full, clear, and exact specification.

My invention relates to compressors, and particularly to compressors of the rotary An object of my invention is to provide an improved compressor. Another object of my invention is to provide an improved compressor of the rotary type. A further object of my invention is to provide an improved compressor of the rotary type capable of compressing a fluid to a substantial pressure and yet so constructed and operating as to be as little wasteful of work during the bringing up of the pressure in the discharge line to the desired pressure as is practicable. A still further object is to provide a rotary compressor especially adapted to efliciently provide compressed fluid at different pressures. Other objects and advantages of my invention will hereinafter more fully appear.

In the accompanying drawings I have shown for purposes of illustration one form which my invention may assume in. practice. In these drawings,- Fig. 1 is a central vertical transverse sec tion through a compressor constructed in accordance with the illustrative embodiment of my invention.

Fig. 2 is a longitudinal vertical section on a plane corresponding to the line 2-2 of Fig. 1.

Fig. 3 is a detail in perspective. H In the form of my inventlon which I have selected for purposes of illustration the same is shown incorporated in a mechanism comprising a casing generally designated 1 and comprising a cen'tral'section 2 and head sections 3 and 4. The central section is provided with intersecting cylindrical bores 5 and 6 in which there are rotatable rotors 7 and 8 which 'are journaled .in any suitable manner, not shown, it being simply requisite that suitable bearings be provided and that one'of the rotors be provided with an extended driving shaft 9 which maybe driven to effect rotation of the rotors. Each of the rotors herein comprises a pair of end the compressor to sections havin oppositely extending spiral tooth blades, t ese sections being designated 11 and 12 and the tooth blades illustrated at l3. Between each pair of sections 11 and 12 there is herein provided a spur gear sec tion 14 whose teeth match with the ends of the tooth blades 13; It will be evident that when a pair of such rotors are arranged in juxtaposition to each other in the casing and with their tooth blades running close to the inner peripheries of the rotor chambers 5 and 6, there will be formed, depending upon the direction of rotation of the rotors, ex-

pansion or compression pockets, and further that air admitted to the spaces between the teeth will be, provided. thedirection of rotation is properly selected, entrapped and compressed and this air may be discharged at any time before the pockets vanish at the line of mesh of the rotors, dependent upon the nature of the discharge means provided.

- For the purpose. of advantageously supplying fluid to the rotors the rotor chambers are caused to communicate with each other substantially throughouttheir lengths b cutting away a portion of the casing, pro ucing' a space as indicated at 15, to which space fluid may be supplied through either or both of the oppositely extending pipes 16 and 17. p

Now briefly considering the mode of o erationof a device "of this sort, it will lie apparent that whether or not there are spaced at the ends of the rotors, i. e., whether or not the rotors at their ends run in close relation to the heads, there will begin to be a compression of the fluid in the tooth pockets when, but only when, the outer extremities o'f the tooth blades on one rotor begin to roll into a tooth pocket on the other rotor.

Accordinglg, if no vent provided for this e uid until the fluid had been comentrap(p presse to a pressure equal to the desired final discharge pressure of the compressor, therewould be a considerable loss'of work during the starting u of the system were isc arge to an empty receiver, as the fluid compressed would simply expand down tosubstantially the pressure in the receiver so that there would be quite a waste of power during the starting of the compressor. -Moreover, were it depressure of the compressor with a discharge sired to reducethe pressure maintained in the receiver to less than the final discharge" designed for the higher pressure, there would be a constant waste of work throughout the entire operation of the compressor. I'have accordingly provided means which will result in a more economical starting of the compressor and will, which is perhaps even more important permit this compressor to operate with various discharge pressures and do so efiiciently.

Means of the sort just referred to may assume various forms, but herein for purposes of illustration I have shown a construction in which the portion of the casing nearest the mesh line of the rotors at the discharge side of the casing is cut away for an extended distance adjacent the center of the rotors and'in suitable guideways 21 there are slidable towards and from each other a pair of members 22 and 23 of such construction that they exactly correspond in cross section to the material which has been removed.

In other words, they are adapted to fit snugly down adjacent'the teeth of the rotois. These members 22 and 23 are provided with ortions 24 and 25 respectively which extend .into cylinder bores 26 and 27 within which bores pistons 28 and 29 are slidable, these pistons being secured to the portions 24 and through-ports 31 and 32. .It will be observed that a spring 33 of suitable strength is arranged in bores in the portions 24 and 25. To the remote ends of the cylinders fluidis admitted from the dischar e chamber 30 of the compressor, this fluid passing 25 and normally forces the members 22 and 23 apart. At this point it is desired to makeit clear that it is not necessary to follow the precise construction shown for the members 22 and 23 ma each obviously be made of a length equa to one-half the-full len h of the rotors and they may be slida le through the heads 3 and 4, if desired there being pockets to receive such portions of these members as may project through the heads at any time. With such a' construction, instead of arranging the pistons 28 and 29 and their corresponding cylinders as illustrated, these would be raised above the sliding members and would be connected the sprin thereto by stems leading to suitable bosses projecting from the upper surfaces of the slides. This would do away with the existence of the pockets 35; and 36 shown, which pockets are necessary herein to permit the requisite movement of the parts 22 and 23, but which in normal operation exert no substantial influence on the operation of the compressor. It will be understood that the greatest rfection of result would however probab y come from the use ofthe longer slides described. v

It will be understood that the strength of 33 will. be proportioned to the areas of t e ad'acen-t'faces of the members '22 and'23, to t e areas of the remote faces between the members, the pressure within the tooth pockets will be substantially equal to or only slightly'above the pressure in the space-30. It will be evident from what has been said that ifthe compressor is starting up and there is no pressure'in the chamber 30 above atmospheric, the membe1s22 and 23 will be spaced apart the maximum distance permitted and so but little compression within the tooth pockets will take place before the entrapped fluid will be brought into communication with the spaces between the adjacent ends of the members 22 and 23. Accordingly, the free expansionof the fluid into the chamber 30 and the dischar e line will be reduced to a Y minimum, s the pressure in the discharge line gradually builds up, the pressure pass- 7 ing through'the ports'31 and 32 will act on the pistons 28 and 29' and will cause the members22 and 23 to ap roach each other and so the discharge ori ce, so to speak, will always bear such relation to' the pockets containing the fluid under compres'sion that these pockets will be brought into communication with the discharge orifice substan-,

tially immediately after the instant when the pressure inthe pocket becomes equal to the pressure in the discharge line. .This will of course-be a much more economical arrangement tha-n would be produced with i an orifice, of constant cross sectional area and it permits, moreover, a compressor which 1S capable of producing and maintaining a pressure'of one hundred pounds,

for example, to operate satisfactorily and without waste of power with a discharge pressure of say fifty pounds, all that is necessary being that the demand for air at fifty pounds pressure be increased or the speed of the compressor be so cut down that so much air will not be discharged into the discharge line as to raise the pressure. The utility and value of this feature will be readily apppreciated by any one skilled in this art. h

. While Ihave in this application specifically described one form' which my invention may assume in practice, it will be understood that this form of'the same is shown for purposes of illustration and that the invention may be modified and embodied in I bers, rotors therei'riiliavin ral tooth blades forming ongitudinally con tracting'compression'pockets, and discharge,

. means comprising a-port-communicablewith said compresslonpockets .for difierent portions oi their existence; 1

2. :IIICQIIlbIIliItlOIl, 1n a compressor, a casmghaving mtercommun catmg rotor chamint'ermeshing Splmeansof gradually ivariable area operative to permit dischargeof fluid from said pockets .as: soon as the pressure therein exceeds the pressure in the discharge lineby a} certain small amount.

'3. ..In combinatiomina' compressor, a casmg having mtercommumcatmg rotor chamberg-rotors therein having intermeshing tooth blades forming compression pockets-,-

- and dischar e means ha'vingf'h; movable charge of fluid from said bounding wa I and operative to-'permit disckets as soon as the ressure therein excee s the pressure in' the schargedmeby acerta nsmall-amounn, 4. In combination, in a compressor, a'casinlghaving intercommunicatmgsrotor chamhers, rotorstherein having inter-meshing spiral tooth blades jormin'gcompresslon pocket s, and discharge'imeans having a. plurality ral tooth of movable bounding-walls and operative to permit Idischarge of fluid from said pockets ass'oonfas the pressure therein exceeds the pressure in the-discharge line by a certain '1 5, lh'pombination, in:a compressor, a casing' having intercommunicating rotor chambers, rotors therein having intermeshing spi-' blades forming compression pockets', and'discharge' means having amovable bounding'wall whose position is controlled so said pockets 'as'soon as exceeds the pressure-in "exceedsthe pressure in thedscharge line by;

by compressor disehar 4 ing .bers,

pressure and oparge of fluid from the ressure therein the d scharge, line by a; certain small amount. Y I

.16. In combination, in a erative to permit disc compressor, a cas-' rotors therein having intermeshingspiral 'tooth'blades formingcompression pock ts and discharge means havin aplur'ahty fof movable bounding walls g whose positions are-controlled by discharge pressure and operative to permit discharge offluid from said pockets'as soonas'the pressure therein a certain small amount.

7 In combination, in "a'compressor, a cas a certain. small amount.

having intercommunicating rotor cham ing having-intercommunicating rotor chain hers, rotorstherein having intermeshing spiral tooth blades' zforming compression pock ets, and dischargemeans having a bounding wall-movable-to diminish the area of the dis-- chargeorifice as compressor-discharge pressure increases and-operatiive to permit discharge of fluid from saidpockets as soon as the pressure'ther'em exceeds the pressure in the discharge line by a certain small amount.

8. In'combination, in a -compressor,- a casing having intercommunicating rotor cham-- bers, rotors therein'having intermeshing spi.,

ets, and discharge means having a plurality of movable walls normally spaced apart and movable in accordance with com re s sordischarge pressure tor edu'ce the e ective area of the compressor discharge means and operative to permit discharge ofifluid from said pockets asso'on as the pressure thereinexceeds the pressure inthe discharge lmej by 9.In a rotary compressor, the combina tion with a pair of rotors each provided with a plurality of teeth cooperating to:

I {pockets de-' 5 creasing in size upon rotation o the rotors,

' of means formin a discharge form between successive teeth port adapted to communicate irectlywith t their imoment of vanish ng and including means for varying the duration of I the 1 er1o' I said discharge port. 1

10. In a rotary compressor, thecombina- I tion with a pair of toothed rotors cooperat-' diminishing in size upon rotation of the rotors,'oi a fluid discharge port communieating directly with the compression pockets and having a 11, In a rotary I nation with a fpair of toothed rotorsco operating to,

e pockets at ofcommunication o f,e ach -pocket with .ral tooth blades forming compression pock- 'ing to form between their teeth pockets bounding edge adjustable in a 1 1 direction perpendicular .to. the plane of the pitch circle o fthe rotor teeth. f

compressor, thefcombi- I no m between their teeth pockets decreasing in size upon rotatlon v of the rotors, ofafluid discharge port having a bounding with which said pockets move during compression and provided with a bounding edge j bl to ary the time-of eommumeation.- v-

1 2. Ina rotary -scompressor,.the*'combination with'a air of toothed rotors 00- operati to I mm I between their teeth pockets ecreasiiiiig 'insize upon rotation o f I id discharge port having a bounding edgeintdcommunication wit which said pockets move and provided with afbounding edge the rotors, of a.

adjustpres'sor discharge. I I I 13. In a" rotary compressor, the combineduring compression edge into communication 'able to-vary the duration of the period "of. I communication of each pocket. with the com- I tion with a casing having a pair of toothed rotors cooperating to form between successive teeth pockets diminishing in size upon rotation of the rotors, of a discharge port opening into the interior ofsaidcasing at a point to'com'm'unicate with'sa-id vanishing pockets immediately prior to their vanish-' ing, and means whereby one dimension of.

said port may be varied to change the period of the latters communication With each of said pockets.

14. In combination, a casing having overlapping bores, a pair of rotors disposed therein and having interme'shing teeth, and

a member movable over the surface thereof.

15. In combination, a casing having overlapping bores, a pair of rotors disposed therein and having intermeshingteeth, and a member longitudinally movableover the surface thereof.

- 16. In combination, a casing having overlapping bores, a, pair of rotors disposed therein and having inter-meshing teeth, and a member disposed adjacent the mesh'lin'e of said rotors and movable longitudinally thereof.

17In a rotary compressor, the combination with a casing having a pair of intermeshing toothed compressor rotors, and

means disposed and movable along a rotor v 4 a 20. In a rotary tion with a casing having a. pair of cooperatlng rotors mountedon' axes always relaperiphery for controlling the pressure ofv the fluid compressed.

18. In a rotary compressor, the combina-v tion with a casing having a pair ofintermeshing toothed rotors, a pressure fluid discharge passage, means disposed and movable along the periphery of said. rotors for the pressure ofthe fluid compressed in said pockets.

compressor, the combinatively fixed, inlet and discharge passages communicating therewith, and meansoperative independentlyofthe inlet passage forcontrolling the degree of pressure to which fluid 1s compressed.-

LEWIS OLAPP.

In testimony whereof I-aflix mysignature. 

